4. Retinal Development

Question 1

What specific growth factors define the foveal avascular zone?

Answer 1

EphA6 and PEDF

Question 2

What does EphA6 do?

Answer 2

regulates the rate of migrating astrocytes and later guides new axons

Question 3

What does PEDF do?

Answer 3

reduces proliferation of endothelial cells in the foveal region

Question 4

Why does the central fovea have a softer surface than the surrounding retina?

Answer 4

1. it has no blood vessels
2. it has no large ganglion cells
   - these large ganglion cells may help resist stretching forces bc of their broad network of lateral connections-parvo ganglion cells in the central retina lack these lateral connection

Question 5

What cells is the central retina dominated by during foveal formation?

Answer 5

midget (parvo) ganglions w/o lateral linkages from large ganglion cells with thin soft axons

Question 6

According to Springer, what causes the indentation in the foveal pit to make the fovea area during fetal development?

Answer 6

rising IOP which pushes the inner retinal layers aside over time to form the fovea

Question 7

What is Springer’s explanation for high cone density?

Answer 7

action of pushing the inner layers out may cantelever the cones back in towards the center of the retina to cause inc cone density
(not widely accepted theory..only account for 1/3 of inc cone density)

Question 8

At 20, 24, and 28 days, what does the

Answer 8

k